Ortho-alkylated phenols are valuable as antioxidants and chemical intermediates. One method of making them is by the reaction of an olefin with a phenol in the presence of an aluminum phenoxide catalyst (U.S. Pat. No. 3,831,898). Phenols have also been alkylated by reaction with an olefin using an alumina catalyst (U.S. Pat. No. 3,367,981). L. H. Klemm et al report the ortho-alkylation of phenol with n-propanol using an alumina catalyst (J. Org. Chem. 45, pages 4320-6).
Much less seems to be known about the benzylation of phenols. W. J. Hickenbottom, J. Chem. Soc., 80, pages 2844-9, report the preparation of 2-benzyl, 2,4-dibenzyl and 2,6-dibenzyl phenols by heating phenol with sodium hydroxide in toluene and reacting this with benzyl chloride.
R. C. Huston et al, J. Am. Chem. Soc. 53, page 2379, describe the reaction of benzyl alcohol with p-cresol using an aluminum chloride catalyst to make dibenzyl-p-cresol.
Brindell et al U.S. Pat. No. 3,816,544 disclose the reaction of 2,6-di-benzylphenol with formaldehyde to form 4,4'-methylenebis-(2,6-di-benzylphenol) but do not disclose any process for making 2,6-dibenzyl phenol.
The most pertinent reference relative to the present invention is believed to be Starks U.S. Pat. No. 4,105,688, which discloses the reaction of phenol and benzyl alcohol in the liquid phase using an .alpha.-alumina monohydrate catalyst to make mainly ortho-benzyl phenol plus minor amounts of 2,6-dibenzyl phenol.